Q: How does my monthly menstrual cycle relate to my hormones?

Posted
Monday, April 21, 2014 3:26 pm

Katherine Melzer-Ross, MD, FACOG.

by Katherine Melzer-Ross, M.D.

A: This article is the first contribution in a series of pieces that will address female fertility and gynecologic issues that women face. While many of us received standard health education classes during our formative years, I frequently encounter patients who are seeking more information about the basic concepts of female fertility, as well as the more complicated matters. The internet has been both a blessing and a curse for physicians and patients alike, as it can serve as a resource for many individuals. However, it can also provide information that is not wholly accurate and is certainly not individualized for each woman’s needs.

A woman’s monthly cycle can seem like a hormonal roller coaster, but it is actually a carefully-timed sequence of events that occur in a predictable manner each month for most women. These synchronized events are tightly regulated by signals from the brain. Each month, the brain sends signals to the ovaries to begin recruiting eggs, which are found within fluid-containing pockets called follicles in the ovaries. Eventually, one egg follicle becomes the strongest of them all (we call this a “dominant follicle”) and this is the egg that becomes destined to ovulate and be released that month. In rare instances, two egg follicles win the race and two eggs are released (this is how non-identical twins occur naturally).

Once the egg is released from the ovary, it is picked up by the nearby fallopian tube. The fallopian tube serves as a transporter, bringing the egg into the tube, where it can be fertilized by sperm. If fertilization occurs, then the resulting embryo is further transported through the fallopian tube into the uterus (the womb) where it implants and grows into a pregnancy. During the time that the ovary has been growing an egg, the uterus has had its own responsibility: to grow a healthy uterine lining where an embryo can implant. Since the uterus serves to provide growing pregnancies with nutrients and blood supply, it is important that the uterine lining develops properly.